1 /*
2 * Copyright © 2010 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24 /**
25 * \file ir_variable_refcount.cpp
26 *
27 * Provides a visitor which produces a list of variables referenced,
28 * how many times they were referenced and assigned, and whether they
29 * were defined in the scope.
30 */
31
32 #include "ir.h"
33 #include "ir_visitor.h"
34 #include "ir_variable_refcount.h"
35 #include "compiler/glsl_types.h"
36 #include "util/hash_table.h"
37
ir_variable_refcount_visitor()38 ir_variable_refcount_visitor::ir_variable_refcount_visitor()
39 {
40 this->mem_ctx = ralloc_context(NULL);
41 this->ht = _mesa_pointer_hash_table_create(NULL);
42 }
43
44 static void
free_entry(struct hash_entry * entry)45 free_entry(struct hash_entry *entry)
46 {
47 ir_variable_refcount_entry *ivre = (ir_variable_refcount_entry *) entry->data;
48
49 /* Free assignment list */
50 exec_node *n;
51 while ((n = ivre->assign_list.pop_head()) != NULL) {
52 struct assignment_entry *assignment_entry =
53 exec_node_data(struct assignment_entry, n, link);
54 free(assignment_entry);
55 }
56
57 delete ivre;
58 }
59
~ir_variable_refcount_visitor()60 ir_variable_refcount_visitor::~ir_variable_refcount_visitor()
61 {
62 ralloc_free(this->mem_ctx);
63 _mesa_hash_table_destroy(this->ht, free_entry);
64 }
65
66 // constructor
ir_variable_refcount_entry(ir_variable * var)67 ir_variable_refcount_entry::ir_variable_refcount_entry(ir_variable *var)
68 {
69 this->var = var;
70 assigned_count = 0;
71 declaration = false;
72 referenced_count = 0;
73 }
74
75
76 ir_variable_refcount_entry *
get_variable_entry(ir_variable * var)77 ir_variable_refcount_visitor::get_variable_entry(ir_variable *var)
78 {
79 assert(var);
80
81 struct hash_entry *e = _mesa_hash_table_search(this->ht, var);
82 if (e)
83 return (ir_variable_refcount_entry *)e->data;
84
85 ir_variable_refcount_entry *entry = new ir_variable_refcount_entry(var);
86 assert(entry->referenced_count == 0);
87 _mesa_hash_table_insert(this->ht, var, entry);
88
89 return entry;
90 }
91
92
93 ir_visitor_status
visit(ir_variable * ir)94 ir_variable_refcount_visitor::visit(ir_variable *ir)
95 {
96 ir_variable_refcount_entry *entry = this->get_variable_entry(ir);
97 if (entry)
98 entry->declaration = true;
99
100 return visit_continue;
101 }
102
103
104 ir_visitor_status
visit(ir_dereference_variable * ir)105 ir_variable_refcount_visitor::visit(ir_dereference_variable *ir)
106 {
107 ir_variable *const var = ir->variable_referenced();
108 ir_variable_refcount_entry *entry = this->get_variable_entry(var);
109
110 if (entry)
111 entry->referenced_count++;
112
113 return visit_continue;
114 }
115
116
117 ir_visitor_status
visit_enter(ir_function_signature * ir)118 ir_variable_refcount_visitor::visit_enter(ir_function_signature *ir)
119 {
120 /* We don't want to descend into the function parameters and
121 * dead-code eliminate them, so just accept the body here.
122 */
123 visit_list_elements(this, &ir->body);
124 return visit_continue_with_parent;
125 }
126
127
128 ir_visitor_status
visit_leave(ir_assignment * ir)129 ir_variable_refcount_visitor::visit_leave(ir_assignment *ir)
130 {
131 ir_variable_refcount_entry *entry;
132 entry = this->get_variable_entry(ir->lhs->variable_referenced());
133 if (entry) {
134 entry->assigned_count++;
135
136 /* Build a list for dead code optimisation. Don't add assignment if it
137 * was declared out of scope (outside the instruction stream). Also don't
138 * bother adding any more to the list if there are more references than
139 * assignments as this means the variable is used and won't be optimised
140 * out.
141 */
142 assert(entry->referenced_count >= entry->assigned_count);
143 if (entry->referenced_count == entry->assigned_count) {
144 struct assignment_entry *assignment_entry =
145 (struct assignment_entry *)calloc(1, sizeof(*assignment_entry));
146 assignment_entry->assign = ir;
147 entry->assign_list.push_head(&assignment_entry->link);
148 }
149 }
150
151 return visit_continue;
152 }
153